1. Technical Field
The present invention relates to image processing. More particularly, but not exclusively, some embodiments relate to locating objects in an image, and/or tracking objects in video streams.
2. Discussion of the Related Art
Tracking physical objects using video data processing is known in the art. For example, WIPO Patent Publication Number WO0141884 teaches a video processor configured for ball tracking in a game of cricket. For each video frame (image), a cricket ball is identified by pixel analysis based upon prior knowledge regarding the shape and size of the cricket ball. The analysis uses image processing techniques that are said in the aforementioned Patent Publication to be “so well known to those skilled in the art that detailed description herein is believed to be unnecessary”.
US Patent Publication No. US2005026689 teaches a system and a method for object tracking. A hand-manipulated prop is picked-up through a single video camera. Each video frame (image) is then analyzed to isolate the part of the image pertaining to the object for mapping the position and orientation of the object into a three-dimensional space. The three-dimensional description of the object is stored in memory and used for controlling action in a game program, such as rendering of a corresponding virtual object in a scene of a video display. Algorithms for deriving the three-dimensional descriptions for various props employ geometry processing, including area statistics, edge detection and/or color transition localization, to find the position and orientation of the prop from two-dimensional pixel data. Criteria are proposed for the selection of colors of stripes on the props which maximize separation in the two-dimensional chrominance color space, so that instead of detecting absolute colors, significant color transitions are detected. Thus, the need for calibration of the system dependent on lighting conditions which tend to affect apparent colors can be avoided.